Four people died and seven others were seriously injured Thursday in a road accident involving three vehicles in southwest Sichuan Province, said local authorities.

The accident happened around 9:40 a.m., when a truck without a license plate collided with two road maintenance vehicles in Luojiang County on a section of an expressway linking the provincial capital of Chengdu and the city of Mianyang, the authorities said.

The 11 victims were all road maintenance workers. The injured were receiving medical treatment in a hospital in Luojiang County, the authorities said.